The overall goal of this research is the complete characterization of the genes coding for the isozymes of fructose diphosphate aldolases in humans. The methods if recombinant DNA technology will be used to isolate and characterize the genes for alsolase A, B, and C. The characterization will involve the determination of the complete sequences, transcriptional units, and the chromosomal location of these genes. The biochemical and molecular biological techniques, including DNA sequences analysis, will be employed for this investigation. The information obtained form these analyses will provide the amino acid sequence of the three proteins, provide an additional test system for relating exon structures to protein domins, and define promoter regions for a class of genes, so called "housekeeping" genes, not previously well studied. A major focus of the study will be the determination of the molecular basis for hereditary fructose intolerance, a disease known to be the result of defects in aldolase B in the lines of affected patients. The proposed studies will precisely define the molecular lesion or lesions responsible for the disease. Several patients who have been confirmed for the disease by biopsy will be selected and asked to participate by informed consent. The genes from affected unrelated patients will be cloned and isolated. Characterization of these genes will be to the level of their primary structures. Nucleotide differences in the gene will be analyzed for their effect on the expression of the gene by in vitro mutagenesis of the mutant gene. Expression of the isolated genes in tissue culture cells will be analyzed. The proposed studies will lead to the development of simple methods for screening patients and detection of people who are heterozygous for the disease. Possible mutations which relate to the transcription and/or control of transcription as well as those which alter the structure and/or catalytic properties of the enzyme will be defined.